# Could someone explain this to me? Trying to constrain lights in Solaris

**URL:** <https://forum.aousd.org/t/could-someone-explain-this-to-me-trying-to-constrain-lights-in-solaris/1589>\
**Category:** USD\
**Tags:** rendering, beginner\
**Created:** [June 10, 2024, 6:48pm UTC](https://forum.aousd.org/t/could-someone-explain-this-to-me-trying-to-constrain-lights-in-solaris/1589 "2024-06-10T18:48:54Z")\
**Posts on this page:** 2\
**Page:** 1

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**Author:** ![Brielle.hans](https://avatars.discourse-cdn.com/v4/letter/b/8e7dd6/32.png) [@Brielle.hans](https://forum.aousd.org/u/Brielle.hans)\
**Post date:** [June 10, 2024, 6:48pm UTC](https://forum.aousd.org/t/could-someone-explain-this-to-me-trying-to-constrain-lights-in-solaris/1589/1 "2024-06-10T18:48:54Z")

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![image](https://us1.discourse-cdn.com/flex016/uploads/aousd/original/1X/d7f24da24def318e2503dfdeeb8cbde06398ae84.png)

I feel like I understand its meaning but not details? Perhaps a simplified explanation could help.

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<div class="post-metadata">

**Author:** ![BigRoyNL](https://sea2.discourse-cdn.com/flex016/user_avatar/forum.aousd.org/bigroynl/32/413_2.png) [@BigRoyNL](https://forum.aousd.org/u/BigRoyNL)\
**Post date:** [June 10, 2024, 9:59pm UTC](https://forum.aousd.org/t/could-someone-explain-this-to-me-trying-to-constrain-lights-in-solaris/1589/2 "2024-06-10T21:59:07Z")

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Might be nice if you could elaborate on where in this description you’re getting stuck. What’s unclear in particular?

In essence it’s saying:

USD is designed to be static / non-dynamic. Hence the nature of a constraint, which is dynamic, is currently not a feature nor a pattern fitting in the current USD ecosystem.

However this does say that, in Houdini’s LOP implementation that acts is that _layer_ above USD it can of course compute a constraint dynamically yet just write the static (or animated) data into USD where it’s not dynamic in nature anymore.

I do agree the wording _can_ be simplified. It uses some terminology that might require some thorough understanding of English and the usage of the word “layer” within a USD context but not meaning an actual USD layer seems like a bad choice.